At the moment, our existing code still uses custom-defined if statements to validate the email and password fields of the Create User request payload object. Since we will be using a JSON Schema validation library for our profile object, we should also migrate our existing validation logic to a JSON Schema to remain consistent. Therefore, let's create a schema for the entire Create User request payload object.

Create a new file at src/schema/users/create.json, and insert the following schema:

{
  "$schema": "http://json-schema.org/schema#",
  "$id": "http://api.hobnob.social/schemas/users/create.json",
  "title": "Create User Schema",
  "description": "For validating client-provided create user object",
  "type": "object",
  "properties": {
    "email": {
      "type": "string",
      "format": "email"
    },
    "password": { "type": "string" },
    "profile": { "$ref": "profile.json#"}
  },
  "required": ["email", "password"],
  "additionalProperties": false
}

There are a few things to note here:

• We are using the format property to ensure that the email property is a valid email, as defined by RFC 5322, section 3.4.1 (https://tools.ietf.org/html/rfc5322#section-3.4.1). However, we also want to exclude certain syntactically-valid emails like daniel@127.0.0.1, which are likely to be spam. Later in this chapter, we will show you how to override this default format.
• We have used a JSON reference ($ref) to reference the profile schema we defined earlier. The $ref syntax was specified in https://tools.ietf.org/html/draft-pbryan-zyp-json-ref-03 and allows us to compose more complex schema from existing ones, removing the need for duplication.
• We have marked the email and password properties as required.